Fluid pump control apparatus for internal-combustion turbine engines



Feb. 23, 1954 L. LEE II 2,669, 38 FLUID PUMP CONTROL APPARATUS FOR INTERNAL-COMBUST TURBINE ENGINES Filed Sept. 15, 1946 ION EMERGENCY o INVENTOR.

LEHHTUN LEE 17 12a Jami 0|. BY Cg APPARATUS AGENT Patented Feb. 23, 1954 UNITED STATES PATENT OFFICE GINES Leighton Lee II, Rocky Hill, Conn, assignor, by

mesne assignments, to

Niles-Bement-Pond Company, West Hartford, 001111., a corporation of New Jersey Application September 13, 1946, Serial No. 696,742

40 Claims. 32

The present invention applies to fuel pump control apparatus for an internal combustion engine, and relates particularly to a dual fuel pump system in which failure of either pump does not impair performance of the engine.

Fuel. pump control apparatus to which the present invention is related is employed for delivering fuel to internal combustion engines, in cluding those suitable for jet-propulsion, propeller-propulsion or combined propeller-and-jet propulsion of aircraft. Such engines usually include an air compressor, one or more combustion chambers, a turbine, and a tail pipe, in the stated order of arrangement. Associated with the engine there is fuel control apparatus responsive to the engine speed, temperature, and altitude of flight, or to some combination of such engine operating conditions, for determining the fuel pump delivery necessary to satisfy the engine opervators requirements in terms of engine speed, torque, or brake-horsepower. The fuel pump control apparatus is therefore responsive to the fuel control apparatus.

It is an object of my invention to provide improved fuel pump control apparatus for an internal combustion engine, said apparatus including two pumps and being responsive to a control pressure supplied thereto which is a function of the desired fuel pump delivery.

Another object of my invention is to provide a dual fuel pump system and improved means for control thereof to render the normal working load on each pump approximately one half the total pumping load, thereby increasing life expectancy and quality of performance of the pumps.

A further object of this invention is to pro vide in such apparatus improved means whereby failure of either pump in such a dual pump system does not impair performance of the engine.

Still further objects of the present invention are to provide improved manually operated means for cutting oif the supply of fuel from the fuel pumps to the engine, and to provide improved means for manually controlling the fuel flow in an emergency created by failure of either the fuel control apparatus or the fuel pump control apparatus.

Other objects and advantages of the present invention will become apparent from a consideracally, fuel pump control apparatus embodying the principles of my invention together with the relationship of such apparatus to an internal combustion engine and to fuel control apparatus associated with said engine.

Referring to the drawing, there are shown the principal elements of an internal combustion engine suitable for propeller-propulsion or propeller-and-jet propulsion of aircraft, as follows: a supporting casing If], an air inlet [2, a multistage compressor indicated as I4, a compressor rotor iii, a combustion chamber l8, a number of fuel discharge nozzles one of which is designated 2%], a generally circular fuel manifold 22, a multistage turbine indicated as 24, a turbine rotor 26 connected to the compressor rotor [6, a tail pipe 23 for discharge of combustion gases from turbine 24, a center bearing 30 and end bearings 32 and 34 supported by casing I0, a propeller shaft 36, and a gear train 38 connecting shaft 36 to I 6.

The principal elements of the pump control apparatus shown in the drawing are identified in the following brief account of its normal operation which is generally defined to indicate fully automatic functioning of all elements of the fuel pump control apparatus in absence of failure of any element whatever. Fuel enters a fuel supply conduit 52 connected to a source of fuel 53 at gine.

a pressure (201) and flows therefrom thru a conduit 56, a primary pump 48 and a secondary pump 66 connected in series with pump 48 by a conduit 64, and from secondary pump 66 at a pressure (102) thru connected conduits 1B and 18,

past a first piston valve 92 in a valving device 42,

and thru a conduit 40 to manifold 22 of the en- The capacity of the primary pump 46 is approximately 10% greater than that of the secondary pump 56, the excess fuel discharged by pump 48 at a pressure (112) being by-p-assed thru a pair of conduits I62 and I58 thru a relief valve mechanism I38 and a conduit I66, thence flowing unrestrictedly thru a control valve mechanism and a conduit Illli, pasta valve I08 in valving device 42, to conduit 50. The relief valve mechanism regulates the pressure (122) in conduits I58, I82 and E4, maintaining this pressure equal to the value of the control pressure which is transmitted to mechanism I38 and 45 thru a conduit l32 and another conduit I30 connected to a fuel control apparatus diagrammatically shown as I23. The control pressure (pc) is a function of the desired fuel flow. The control valve mechanism 45 is connected to conduit l8 and regulates the pressure (:03) therein and hence the pressure downstream from secondary pump 66 by allowing part of the fuel discharged by pump 68 to flow thru mechanism 45 3 into conduit I I16 and thence past valve I88 in valving device 42 to conduit 58 at the pressure (pi). The pressure (pa) in conduit I8 is regulated in response to the control pressure (17c) at a value approximately twice that of pressure (p6). Since, in normal operation, (pz:pc), the pressure rise across pump 48 is approximately (270-171), and, since the pressure (paw2pc), the rise across pump 66 is approximately (219F420); whence it follows that, considering (121) to be approximately atmospheric or other relatively low pressure, the rise across each pump is approximately equal to the value of gage pressure (2-70), the rise across both pumps being approximately (210C). The ratios (name) and (P322712) and hence the ratio (pszpz) may be selected to provide any desired distribution of the total load between pumps 48 and 66.

The range of values of the control pressure (120) is predetermined by the design of fuel control apparatus I28, the pressure (17c) being some function of such engine operating conditions as speed, torque, and brake-horsepower. The demand for fuel increases as the brake-horsepower increases, as the speed increases when the torque is constant, and as the torque increases when the speed is constant. In the embodiment shown the control pressure (130) increases as the desired fuel flow increases. It is conceivable, however, to employ fuel control apparatus providing a control pressure decreasing as fuel fiow increases, in which case a modification of the fuel pump control apparatus shown in the drawing is necessary. In design of the fuel pump control apparatus, the capacity of secondary pump 56 must be slightly greater than necessary to satisfy maximum fuel requirements of the engine at the lowest value of engine speed applying to such maximum fuel flow. Prerequisite to design of the apparatus shown is provision of a range of values of control pressure (in) having an approximately 1:2 ratio with the corresponding values of the corresponding range of the pressure (pa) of fuel delivered to the engine.

The valving device 42 is responsive to movement of a manually operated valve control lever I22 to cut off the flow from conduit I8 to conduit 40, thereby cutting off the flow to the engine and stopping the operation thereof.

In addition to the elements identified in the foregoing brief account of normal operation of the embodiment shown, there are two check valve mechanisms Ilil and H38, respectively, and additional conduits which are required in the event of certain types of failure of one or more of the identified elements, as hereinafter described.

Again referring to the drawing in detail, the primary pump 48 is shown to include a body 54 having therein a pair of gears 55 and 58. Gear 58 is rotatable on a shaft 68 by gear 58, and gear 58 is fixed to a drive bushing 59 which has a splined coupling 6! connecting it to a main drive shaft 62 thru a shear pin I53. In the embodiment shown, shaft 52 is rotated by the engine at a speed proportional to the engine speed, but other suitable means of driving the shaft may be employed if desired.

Conduit 64 connects the outlet of primary pump 48 to the inlet of secondary pump 66 which is of approximately ten per cent less capacity than pump 48 but of similar construction, the normal delivery thru pumps 48 and 66 being substantially constant at any given value of pump speed when the mechanical condition of the pumps in respect to wear and pump clearances is substantially constant. Included in pump 66 there is a body 68 having therein a pair of gears 78 and I2. Gear "I8 is rotatable on a shaft 14 by gear 12 which is fixed to a drive bushing I3 having a splined coupling I5 connecting it to main drive shaft 62 thru a shear pin 77. Drive bushings 59 and I3 are rotatable in fixed bearings I9, (H and 83. Provision of shear pins 63 and I1 is to forestall complete failure of the apparatus in the event of failure of a single pump. Thus, if either pump binds and the torque required for its rotation exceeds a predetermined value, the corresponding shear pin fails, stopping the one pump and allowing operation of the other to continue. Failure of either pump, therefore, resulting from binding or any other cause of stoppage or excessive torque does not impair rotation of the other.

The outlet of secondary pump 66 is connected by conduit It to conduit I8 which, in turn, is connected thru valving device 42 to conduit 40. Conduit I8 is also connected to control valve mechanism 48 and, thru a passage R8, to check valve mechanism 80, which is normally closed.

Valving device 42 includes a body 82 having therein a pair of parallel cylindrical bores 84 and 88, the left ends of which are closed by body 82. Near the right-hand ends of bores 84 and 86 there are two annular grooves 88 and 90, respectively. Groove 88 is connected to conduit 48 and a chamber I84 at the right-hand end of bore 84 is connected to conduit I8. Flow from conduit I8 to conduit 48 is controllable by means of piston valve 82 which is slidable in bore 84 in response to movement of .a gear 94 mounted on a control shaft 85. Gear 84 engages a centrally located toothed portion 98 of the valve length which has a somewhat smaller diameter than that of bore 84. A channel I is provided in the valve to equalize pressures in chamber I04 and a corresponding chamber I82 at the left-hand end of bore 84, and to permit sufiiciently rapid movement of a substantially leak-proof piston.

Similarly, groove 98 in bore 86 is connected to conduit 50 and a chamber I [6 at the right-hand end of bore 86 is connected to conduit I05. Flow between conduits I08 and 58 is controllable by means of piston valve I88 which is like valve 92 and is similarly slidable in bore in response to movement of gear 94 in relation to a toothed portion H0 01 valve I08. A channel H2 is provided in valve I08 to equalize pressures in chamber H6, and a corresponding chamber i I4 at the left-hand end of bore 86.

Shaft 98 in valving device 42 is connected to a shaft I I8 rotatable in a fixed bearing I20. The manually operated valve control lever I22 is fixed to shaft H8 and is rotatable thru. an arc deter mined by a pair of stops I24 and I25 which are located so that, when lever I22 is moved to the emergency position at the extreme limit of counterclockwise travel, gear 94 moves valve 92 leftward from the normal position shown in the drawing and simultaneously moves valve I08 to ward the right to block groove 90, thereby closing the passage between conduits I06 and 50. Similarly, when lever I22 is moved to the cutoff position at the extreme limit of clockwise travel, gear 94 moves valve I08 leftward from the normal position shown and simultaneously moves valve 92 toward the right to block groove 88, thereby preventing flow from conduit I8 to conduit 40.

In the normal position shown, lever I22. is vertical and valves 92 and I08 just clear grooves fuel control apparatus I28.

*sure (in) in chamber I52.

In relief valve mechanism I33, the effective area (A) of bellows Mil equals that of piston I50. Since the opposite forces acting on piston I50 'due to identical pressures (232) in chambers I56 88 and 90, respectively. In this position, there is negligible or no pressure loss as flow occurs between conduits I and 40, or between conduits I and 5d, Leftward movement of either valve from the normal position does not increase the past itself, the amount of such. restriction depending on the extent of movement of lever I228 from its normal or vertical position. The valve control lever I22 is not to be confused with the engine control lever generally associated with the The fuel control apparatus I23 normally provides a control oil pressure (1:10) which is a measure of the desired fuel flow to the engine. Conduit I is connected to apparatus I28 for the flow of control oil at pressure (500) to conduit I 32, the left-hand and right-hand ends of which are respectively connected to a closed chamber I34 in pressure control valve mechanism and to a closed chamber 36 in relief valve mechanis Relief valve mechanism E08 has a body 41 with a generally cylindrical hollow interior, the upper fined by cylinder I42, step Ml, and the exterior surface of bellows I40. i

A stem E48 attached-to the lower side of tbe' upper end of bellows I45 serves to transmit motion of bellows ME to a piston. valve 550 which is slidable in cylinder I44. A chamber I52 below piston Hill is connected by a channel M4 in the piston to a chamber I55 inside bellows I46, the

pressures in chambers I52 and lei; thus being equalized. An annular groove FM, in guide M4, is connected to conduit I% for permitting flow of fuel along a path including conduit I 53', chamber I52, groove ltd, and conduit I85, in the stated order. When such flow occurs, motion of piston I50 is eifective to vary the effective area of flow into groove It -l, thereby varying the presand I52 equal and therefore ineffective to produce motion of the piston, the position ofpis ton I50 is controlled by a balance between two other forces, as follows: a downward'iorce (pea) due to the pressure 10s) in chamber Itfi acting on bellows Md and an opposing forcelA the pressure in chamber I52) acting on the piston, Piston I59 seeks a position at which the stated forces are in equilibrium or at which the pres- :sure 12) in chamber I52 equals the control. pressure e) It is apparent therefore that the sure (in) in conduits I cc, IE2, and 5.4 is main-.

tained at the value of the control pressure (pr) of oil supplied to the fuel pump control appara- -tus by the fuel control apparatus i223.

Pressure control valve mechanism it includes a housing 553 in the upper end of which there a generally cylindrical cavity 720%! having asits centerline the vertical centerlin'e of housing its.

of bellows 202 and 204.

contract, valve 22s first closes ports valvc ZZbcloses port .230. I .'The' position ofxpiston' 2l l,..and hence the poriphery of cavity 200. A second bellows 204 inside bellows 202 has its respective ends fixed to the upper end of bellows 202 and to the lower end of cavity 200. A chamber 206 thus formed between bellows 202 and 204 is connected to a conduit 44 for transmission of the compressor inlet pressure (93 from the engine to mechanism 4B.

A circular opening 208 is provided in housing Iat the lower end of cavity 200 at the approximate center of the lower end of bellows 204. Housing I98 is extended downward from the opening 208 to form a substantially cylindrical shell 209 which serves to retain a valve guide 2 I0 which is pressed into shell 209. Use of separate pieces I08 and M0 is for the purpose of facilitating machining of the guide 2 I0.

Guide 2!!! has a cylindrical bore 2 I 2 in line with opening 208, the lower end of bore 2I2 being closed by the end of guide 2I0. A piston 2 I4 connected to the top of bellows M4 and hence ,to the top of bellows 202, by means of a stem MB, is slidable in bore 212 in response to movement There is a chamber 2| 8 below valve 2 I4 to which conduit I8 is connected. The respective pressures in chamber 2I8 and in a chamber 220'above valve 2I4 and inside bellows 284 are equalized by provision of a channel 222 in piston 2I4. Piston 2 I4 is of a generally cylindrical shape and has an undercut 224 which provides an upper valve 226, a lower valve 228, and an annular chamber 229 inside bore 2I2.

Bore 2I2 of guide 2l0 has an upper port 230 connecting chamber 229 to an upper annular groove 232 on the outside of guide 2I0. Conduit I555 is connected to groove 232 and hence to ,At the upper end of groove 2536 two like apertures 240 are provided in guide 2H3 which afford a passage of constant area from chamber 229, thru apertures 240, and past groove236 to conduit I06 so that flow along this path is always unrestricted, the pressure in chamber 220 therefore always equaling. the pressure (an) in conduit I06 when bellows I02 and H24 are not sufvficiently contracted tocause closure of port 230.

At the lower end of groove 235 a pair of ports 242 is provided iii-guide iIll which provide passage from chamber Ziii to groove 23t and into conduit illii. Any suitable number of ports 222 may be employed. Ports 242 are valved by the lower edge of lower valve 228, thereby restricting the area of flow from chamber 252 to conduit I06, when bellows 2312 and. ti are sufliciently contracted, the degree of restriction depending upon the position of valve 228. Valves 22B and 228 and ports 240 and 242 are so disposed in relation to each other that. as bellows 202 and 204 242 and then -sition of, valves and228, is-determinegl solely 51 by the balanceoi forces acting on bellows Ztiland 204,- since the same pressure (pa) in chambers 220 and 216 acts directly on the piston to produce (Downward force) =(sum of upward forces) in which (A) and (a) are the effective areas of bellows .202 and 264, respectively. The quantity (Aa) is of small value and the value of pressure (20 isalso, small compared with the respective values of the pressures (pa) and (pa) Therefore, the force [FHA-41)]- in the above equation is small and is neglected in the present discussion for purposes of simplification, whence it is possible to say that:

In theembodiment shown, the area, (A) of bellows 282 is approximately twicethearea (a) of bellows 204; or (A)-2(-a It is apparent, that (m) :(m) 2 or that the value of themessure (in) in chamber 2 I8 is approximately equal to 2(1 e) in normal operation. The normal function of control valve mechanism 46 is to regulate the pressure (pa) in this substantially constant relationship with the control pressure ('17:).

NORMAL OPERATION-SUMMA'RY Equally cfilcient primary and secondary pumps In normal operation, valve control lever I22 is in its normal" or vertical position; unrestricted flowmay then occur thru valve mechanism 42, from conduit 18 to conduit 40, and from conduit I 06 to conduit 56. Also, relief valve mechanism I36 regulates the pressure (102) at the outlet from primary pump 48 and hence at the inlet to secondary pump 66, at a value approximately equal to the value of the control pressure (170) supplied by the fuel control apparatus I28. Similarly, the

control valve mechanism 46 regulates the pressure subject; to wear resulting from carrying the entire pumping load. In normal operation, with both pumps about equally efficient, all fuel en tering secondary pump 66 is delivered to it-thru conduit 64 from primary pump 46.

When valve control lever I22 is moved. clockwise to "cut-off position, valve 62 in device 42 movestoward the right and blocksflow from conduit 18 thru chamber I04 and port 86 into conduit 46, regardless of the value of the. control oil pressure (110). Cut-off is thus rendered immediately responsive to movement ofle'ver I22 without any time lag such as might result biz-stopping th=erigineby first reducing the control oil pressure (pt). V normal cut-off, continues to be regulated by The value of the pressure (pa). in

mechanism 46 vas a function of the control oil pressure (17c) there being no abnormal strain imposed onthe system by movement of lever I22 to cut-off position.

Primary pump failure When the primary pump 48 fails owing to stoppage or excessive torque, shear pin 63 fails,

thereby allowing drive shaft 62 to rotate in splined coupling 6|. and the secondary pump 66 continues to operate at the corerct speed. Failure of primary pump 48 may also occur as a result of wear or other cause of. a reduction of capacity which prevents it from maintaining a desired value (m) of fuel pressure in conduit 64. In general, therefore, failure may be considered a Prohibitive capacity decrease whether such decrease is. caused by wear or leakage due to inefficiency of a pump being driven at the correct speed or by reduction of the. pump speed to zero. by shear pin failure. 7

When primary pump 48 fails so that mechanism I38 cannot regulate the pressure in conduit 64 and hence at the entrance of secondary pump 66 at a value as great as that of the control pressure (Po) relief valve mechanism I36 responds by lowering piston I56 to an extreme position at which the annular groove I64 is blocked off and flow from conduit I62 to conduit I66 is stopped. Thus, no pressure loss occurs in conduit 64 as a result of flow thruconduit I62 when the pressure (172) in conduit 64 is less than that of the control pressure (pc), and all fuel delivered by primary pump 48 to conduit 64 enters secondary pump 66, under this condition.

The capacity of secondary pump 66 is sufliciently great to supply all fuel required by the engine at the value of the pressure (pa) determined by the control oil pressure (pc) acting in the control. valve mechanism 46. As the pressure in conduit 64 decreases the pressure differential acting across secondary pump 66 is required to increase accordingly, pump 66 being subjected to the load. imposed by the total normal differential across both pumps, when primary pump 48 fails completely, or to an increased load corresponding it; the degree of partial failure of primary pump As the flow from primarypump 48 into conduit 64 decreases because of the failure referred to, secondary pump 66 continues to supply conduits I6 and I8 with sufilcient fuel to maintain the value of pressure (pa) determined by mechanism 46. Since secondary pump 66 cannot obtain suflicient fuel from primary pump 46, however, the value of the pressure (pa) in conduit 64 continues to fall below that of the control pressure (so. When the value of pressure (pa) in conduit 64 becomes less than the value of pressure (in) in conduit 56, provision is made for the flow, of fuel from conduit 50, and thru a conduit I82: and a check valve mechanism I80,.into a conduit I84 and thence to conduit 64, thereby lay-passingprimary pump 48 and permitting secondary pump 66 to operate at full capacity but at the greater rise measured by the increased value of the diiferential (pa-pz).

Check valve mechanism I86 includes a housing I86 and a ball valve I88 movable in a chamber I60, chamber Iii!) being connected to conduit I84 and being separated by a seat I62 from another chamber I94 which is open to" conduit I62. When the pressure (pa) in chamber I96 exceeds the pressure (pi) in chamber I94, ball valve I68 moves upward. to seat 192, thereby preventing viously defined.

flow thru mechanism we. As previously indicated, however, when the pressure (pa) in chamber I 90 is less than the pressure (321) in chamber !94, ball valve I88 moves downward to a step 196 in chamber is!) to allow fuel to flow thru check valve mechanism I86 along the path pre- If desired, a spring may be used to bias ball valve its toward open position in order to permit opening of the valve in response to a smaller decrease of pressure in conduit as when primary pump 48 fails.

It is thus apparent that, when primary pump 48 fails owing to inefficiency or stoppage to pump sufficient fuel into conduit 6 3 to maintain the value of pressure (:02) equal to that of the control pressure (pt), secondary pump v36 assumes the entire load or whatever increased load is necessary without changing the fuel flow to the engine and hence without impairing engine operation. In order to accomplish this, piston I58 moves to shut fuel flow across mechanism I38, and

check valve mechanism i853 operates to icy-pass fuel around pump it to conduit i3 5 and hence to pump 66.

Secondary pump failure When secondary pump (it; fails owing to stoppage or excessive torque, shear pin ll fails, thereby allowing drive shaft $2 to rotate in splined coupling is, and the primary pump as continues to operate at the correct speed. Failure of secondary pump may also occur as a result of Wear or other cause of a reduction of capacity which prevents it from maintaining desired values of the volume of flow and of the pressure (he) in conduit l8. As is true of primary pump t8, failure of secondary pump 56 may be generally ascribed to prohibitive capacity decrease. whether such decrease caused by wear or leal age while the speed is correct, or by reduction of the pump speed to zero by shear pin failure.

When secondary pump t5 fails to produce a desired value of the pressure (p3), primary pump 48 response by assuming whatever increased load is necessary to maintain pressure (103') at the desired value. corresponding to a given engine operating condition, the fuel delivery from primary pump 63 is constant; it is apparent that, when a normal proportion of the fuel discharged by pump 48 does not pass thru secondary pump the pressure in conduits G l, it' l, i532 and let increases to a value greater than the value of the control pressure (32). The initial effect produced by this pressure increase is to cause piston 55!] in I relief valve mechanism E38 to open to reduce the pressure (322) to the value of pressure (he). Thus mechanism its will not allow pressure (p2) to exceed pressure (pt) as long as there is unrestricted flow from conduit J55 across mechanism 45 to conduit we as has been the case thus far. Depending upon the nature and extent of failure of secondary pump 65, however, while mechanism i538 tries to maintain pressure (292) at the value of pressure (232), the pressure in conduit is has a value between zero and a value somewhat less than that of the pressure (pt), since all fuel entering conduit it must pass thru pump lisfrom conduit As the pressure (103) in conduit [8 falls below the pressure (100) the control valve mechanism 66 responds by contraction of bellows 2532 and 253s until valve 223 closes port 242, the bellows continuing to contract until valve 226 restricts port 236. The regulation of the pressure (pa) in conduit 18 thus becomes a function Since, at any given pump speed of valve 225 in relation to port 239 rather than of valve 22-8 in relation to ports 242 as is normally the case. Since the fuel flowing into conduits 16 and 78 from pump 66 is insufiicient to maintain the pressure e) in conduit ill at a desired value, bellows 232 and hi l in mechanism ill would continue to contract until valve closed port 23!), there then being no fuel whatever flowing from conduit E l thru conduits I62 and lit to mechanisms lit and As the pressure (p1) in conduit Hi2 becomes equal to or exceeds the pressure (103) in conduit iii, however, which it does when pressure (p2) is only slightly greater than (pc), flow of fuel permitted along a path from conduit are, thru a check valve mechanism 8%, and thence thru conduit H8 to conduit it. The pressure (pa) in conduit it is thereby restored to desired value and its regulation by mechanism it is accomplished by movement of valve 226 in respect to port 1233. Check valve mechanism 8!? comprises elements identical with those of mechanism [3d, conduits 553 and H8 being related to mechanism 8!] as conduits I82 and I84 are related to mechanism 180.

Thus, when the secondary pump it fails, owing to inefiiciency or stoppage, to pump sufiicient fuel into conduits 16 and it to maintain a required value of the pressure (p3) primary pump 13 assumes all or Whatever additional load is required. In this condition of the apparatus, check valve mechanism 89 is open, relief valve mechanism 138 is ineffective, and regulation of pressure (193) is accomplished by the movement of valve 226 in mechanism M3 in relation to port 23! Fuel flow to the engine is unaffected and hence the engine performance is unimpaired by such failure.

Control valve failure-both pumps operating In the event of failure of control valve mechanism 46' in a manner which prevents it from regulating pressure (113) Whether or not as a result of a bellows leak or other cause, piston 2 l4 moves upward or downward from its correct position depending upon the nature of such failure. The failure is made apparent by faulty engine performance.

When mechanism 46 fails and the fuel flow is low as is the case when pressure (113) is less than desired, valve control lever I22 is moved counterclockwise toward the emergency position, thereby causing valve |08 to restrict the flow of fuel from conduit I06 across valving device 42 to conduit 50. As such restriction is increased, the pressure (213) in conduit 18 increases and the position of the lever I22 is determined to produce the desired engine speed.

When mechanism 46 fails and the fuel. flow is high as is the case when pressure n) is higher than desired, valve control lever I22 is moved clockwise toward cut-off position, therebycausing valve 92 to restrict the flow of fuel from conduit 18 across valving device 42 to conduit 40. As such restriction is increased, the fuel flow to the engine decreases but the pressure (123) continues to remain higher than normally desired. In this case, control of fuel flow is accomplished by regulating the effective area of flow past valve 92 rather than by regulation of the pressure (113). ihe position of lever I22 is determined to produce the desired engine speed.

Manual control of fuel flow to either increase or decrease the flow disturbs the normal relationship between the respective functions of mechanisms 46 and I38 and between the pressures (106), (p2), and (113). Similarly, failure of mechanism 46 disturbs the normal relationship between the respective loads on the pumps, the effect being most serious when mechanism 4% fails in a manner which completely stops flow into conduit I06. When this occurs, the pressure (102) increases to a value which is a function of the speed and capacity of primary pump 48, the pressure (pa) in conduit 18 correspondingly increases and hence the fuel flow increases. It is provided, however, that shear pin 63 associated with pump 48 fails under a lower overload than the corresponding pin 11 associated with pump 66 -so that on occurrence of such failure of mechanism 46 pump 48 fails and pump 66 assumes the entire load. Proper movement of lever I22 toward cut-off will then reduce flow to the engine, cause deceleration, reduce the speed of pump 66, and enable the operator to maintain manual control for the duration of the emergency. The possibility of such failure is relatively remote since it is principally causable by binding of piston 2 l4 in guide 2l2 and dependable means of avoiding such sticking are subject to provision in design,

Relief valve failure engine is in correct relationship with the control oil pressure (pt). If the failure causes piston I50 to rise so that pressure (102) has a low value approximating that of the pressure (pi) in conduit I06, pump 48 carries little or no load and pump 66 carries the enti're load, drawing fuel n 'thru check valve mechanism 180 and requiring the apparatus to function about as in the case or primary pump failure previously explained.

In all cases; ln'anual regulation of the pressure (in) a" "d hence manual regulation of the rate of reel to the engine is an emergency measure,

the character of regulation being dependent upon 'Ethe condition ef flight and the skill of the opera- Failure (if either control valve mechanism 46 or relief valve mechanism I38; 01' of both, may resu1t a (rendition suustanuauy equivalent to failure of the fuel control apparatus 128 which results in faulty regulation or the control oil pressure (he). find other means of emergency control are available, lever F22 may be operated to provide manual control of the pumps when such -f'ailure or the ine], control apparatus occurs.

want the embodiment of myinvention shown and described herein specified use of collapsible bellows as pressure responsive means, the invention does not preclude employment of pressure responsive p'i's'ton's, diaphragms, or other suitable -'riieans.

Other terms and expressions "which I have em moves are used as terms'oi description and not of "limitation, and I "have no intention, in the use of such terms and 'e'irpressions, of excluding any as sociatdtherwith a source 'of fluid, a conduit 7 mechanism having for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of said fluid flow and hence said speed; comprising: a connection for the flow of fluid from said source to said conduit, a pair of pumps in series in said connection for producing said flow, and means responsive to said control pressure for regulating the respective pressures in said connection between said pumps and in said conduit, so that said fluid flow and the speed of said mechanism are each a selected function of said control pressure.

2. Fluid pump control apparatus for a rotating -mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid flow and hence said speed; comprisins: a connection for the flow of fluid from said source to said conduit, a pair of pumps in series in said connection for producing said flow, first means responsive to said control pressure for regulating the respective pressures in said comnection between said pumps and in said conduit; and second means effective, when one of said pumps fails so that said first means cannot maintain said conduit pressure at a value corresponding to a predetermined function of said control pressure, to cause the other of said pumps to deliver iiuid to said conduit from said source so that said first means restores said conduit pressure to said predetermined value; whereby said conduit flow and hence the speed of said mechanism are predetermined functions of said control pressure.

3. Fluid pump control apparatus 'for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid flow and hence said speed; comprising: connecting means including a pair'of pumps in series therein for delivering fluid from said source to said conduit, first means for operating said pumps including a pair of shear pins, on:

" of which is subject to failure when the torque re quired to operate the corresponding pump "exceeds a predetermined value; second means effective, when said shear pin corresponding to either of said pumps fails, to cause the other of said pumps to produce flow to said conduit from said source, third means responsive to said control pressure for regulating said conduit flow by regulating the pressur in said conduit in a preselected relationship with said control pressure; and manually operated means ior'overriding said third means to control said conduit now; whereby said conduit -ilowand hence the speed of said mechanism are functions of said control pressure, said conduit flow is not affected by failure of either of said pumps, and whereby said speed is also subject to manual override control.

4. Fluid pump control apparatus for a rotating mechanism having associated therewith a source of fiuid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate of said iiuid flow and hence said speed; comprising: a connection for the flow of fluid from said source to said conduit, a pair of pumps in series in said connection for producing said flow, means responsive to said control pressure for regulating the respective pressures in said connection between said pumps and in said conduit so as to maintain the respectiv values of the pressure differentials across said pumps in a substantially constant predetermined relationship with each other, and manually operated means for varying the effective area of flow thru said conduit from a maximum value at which said flow is unrestricted to a zero value at which fuel flow to said mechanism is cut off, whereby said flow is a function of said control pressure and of said manually operated means.

5. Fluid pump control apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid fiow,-and a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid fiow and hence said speed; comprising: a connection for the flow of fluid from said source to said conduit, a pair of pumps in series in said connection for producing said flow, first means responsive to said control pressure for occurs to increase the pressure rise across said other pump by an amount corresponding to the degree of said failure, thereby compensating for said failure and maintaining said conduit pressure at the value determined by said first means; whereby the speed of said mechanism is a function of said control pressure and is not affected by failure of one of said pumps.

6. Fluid pump control apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid flow and hence said speed; comprising: a connection for the flow of fluid from said source to said conduit, a primary pump and a secondary pump in said connection, said primary pump being normally operable to deliver fluid from said source to said secondary pump and said secondary pump being normally operable to deliver fluid to said conduit, first means for regulating a first pressure in said connection between said pumps at a first predetermined proportional value of said control pressure, second means for regulating a second pressure in said conduit at a second predetermined proportional value of said control pressure which determines saidconi4 duit flow, said first and said second Dredeter-. mined proportional values being in a substantially constant preselected relationship with each other whereby the respective pressure differentials across said primary and said secondary pumps are in a corresponding substantially constant relationship with each other; a channel for the flow of fluid from said source to the inlet of said secondary pump, valve means in said chan-. nel effective to prevent fiow therethru when said first pressure has said first predetermined proportional value; said valve means being also effective, when said primary pump fails so that. the value of said first pressure decreases more: than a pre-established amount below said first predetermined proportional value, to permit flow thru said channel; the value of said pressure differential across said secondary pump increasing, when said primary pump failure occurs, an amount substantially equal to the decrease in value of said first pressure so that the value of said second pressure i maintained at said second predetermined proportional value; whereby the speed of said mechanism is a function of said control pressure and is not affected by said primary pump failure.

7. Fluid pump control apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof,- means for rotating said mechanism at a speed determined by the rate of said fiuid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate, of said fluid flow and hence said speed; comprising: a first connection for the flow of fluid from said source to said conduit, a primary pump and a secondary pump in said first connection, said primary pump being normally operable to deliver fluid from said source to said secondary pump and said secondary pump being normally operable to deliver fluid to said conduit first and second channels, respectively, for the flow of fluid from the outlets of said primary and; secondary pumps to said source; first and second valve means, respectively, in said first and sec ond channels for regulating the fuel flow therethru, said first and second valve means; being responsive to said control pressure and efiective to regulate first and second pressures respectively at the outlets of said primary and said secondary pumps at first and second proportional values of said control pressure; said conduit flow being a function of said second pressure; third and fourth channels respectively for the flow of fuel between said source and the inlet to said secondary pump and between the outlet from said primary pump and said conduit, third and fourth valve means respectively in said third and fourth channels responsive to the respective differentials thereacross for regulating the flow therethru, said third and fourth valve means being normally effective to prevent flow therethru when the values of said firstand second pressures respectively equal said first and second proportional values of said control pressure; said fourth valve means being also effective when said secondary pump fails so that the value of said second pressure falls below said second proportional value to permit flow thru said fourth valve means thereby restoring said second pressure to said second proportional value and increasing the pressure rise across said primary pump an amount corresponding to the extent of said failure of said secondary pump; and a second, connection bee tween said first and second channels so thatwhen said secondary pump failure occurs, said second valvemeans stops .flow thru said second chan-v nel and overrides said first valve means to regs ulate the flow thru said first channel; whereby said conduit flow and hence the speed of said mechanism is a function of said control pressure and is not affected by said secondary pump failure.

z 8. Fluid pump control apparatus for a rotating mechanism having associated therewith a source 01 fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, meansfor rotating said mechanism at a speed determined by the rate of said fiuid flow, and a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid flow and hence said-speed; compris ing: a primary pump having the inlet thereto connected to said source, a secondary pump have ing the outlet therefrom connected to said con -v duit, a first connection for the fiow oi fluid from said primary pump to said secondary pump, said primary pump normally supplying fluid to said connection at a predetermined rate greater. than the corresponding rate of flow fromsaid' sec ondary pump to said conduit, a second connection for the flow of fluid from said conduit to said source, a third connection for the flow of fiuid from the outlet from said primary pump to said a second connection, first valve means in said third connection for regulating the flow therethru; second valve means in said second and said third connections for regulating the flow therethru, said second valve means being normally ineffective to affect the flow from said first valve means to said source, said first and second valve means being responsive to said device and normally efiective to regulate first and second pressures re spectively at the outlets from said primary and said secondary pumps at first and second proportional values of said control pressure so tliat'the respective values of the pressure dilferentials across said primary and said secondary pumps are in substantially constant preselected relationship; said second valve means being efiectiva when said secondary pump fails to produce fiow-therea thru, to override said first valve means and'to regulate said first pressure at said second proportional value of said control pressure; means ior flowing fluid from said primary pump to said conduit when said failure occurs, and first mam ually' operated means for overriding said secondwalve means to regulate said flow in said conduit by varying the effective area of flow thru said conduit, whereby said conduit flow is a function of said control pressure and said manually operated means, and whereby failure of said secondary pump does not affect said conduit fiow.

9. Fluid pump control apparatus fora rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid fromsaid source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said fluid flow which is a function of the pressure in said conduit, a device for producing a control pressure in said apparatus which is a function of the desired rate of said fluid flow, and a pump control lever; com

prising: a first connection between said source and said conduit, a primary pump and a secondary pump downstream therefrom and in series therewithin said connection for producing said conduit flow, first means for by-passing a part of the fluid discharged from saidprimary pump tosaid.source,second means including a valve and a bellows responsive to said control pressure for operationrof said valve, said valve being ef fective to control said first meansin order to reg uiate a first pressure. in said first connection bee tween said pumps at a first predetermined proportional value of said control pressure, third means for .by-passing a part of the fluid dis charged from said secondary pump to. said source, fourth means including a valve and a pair, of bellows responsive to an operating pressure in said mechanism and to said control pressure for operation of said valve, said valve. being efiective to control said third means in order to regulate said conduitpressure at a. second predetermined proportional value of said control pressure, said first and 7 second predetermined proportional values being effective to maintain the respective values of the pressure differentials across said pumps in a substantially constant preselected relationship with each other, fifth and sixth means responsive to said pump control lever for overriding said second means and said fourth means to control said conduit flow, said fifth and sixth means being ineffective to vary said conduit flow when said lever is in a predetermined normal position, said lever being efiective upon movement from said normal position to cause said fifth means to progressively decrease the area of flow thru said conduit downstream from said fourth means or to progressively increase the-pressure downstream from said sec-.- ond and third means so that said conduit. pres!- sure is increased from a minimum value corresponding to the value of said control pressure to amaximum value corresponding to the maximum capacity of said pumps, whereby said speed is normally a function of said control pressure and is subject to override control by said pump control lever to increase or decrease the speed of said mechanism.

' 10. Fluid pump control apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fiuid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of said flow, a device for producing a control pressure in said apparatus which is a function of the desired rateof said fluid flow,'and a pump control lever; comprising: a pair of pumps in series in said conduit, a driving means for simultaneous operation of both pumps at identical pump speeds; the respec tive deliveries thru said pumps having rates determined by first and second pro-established empirical functions ofsaid pump speed, the respective'torque loads imposed on said driving means by said pumps having values determined by third and fourthpro-established empirical functions of said pump speed and of the respective values of the pressure rise across said pumps, and said flow to said engine having a value determined by a fifth pro-established empirical function of the sum of said respective torque loads; a pair of pins for connecting said pumps to said driving means for transmitting said torque loads from said pumps to said driving means and adapted to fail so as to remove said torque loads from said driving means When said torque loads exceed 'pre-. determined values, said failure of one of said pins removing the load of the corresponding pump from said driving means so that the speed of saiddriving means is not affected and whereby operation of the other of said pumps continues uninterruptedly, control means responsive to said device for varying the respective values of said torque loads in accordance with predetermined functions of said force measure, said control means also being normally effective to maintain the respective torque loads of said pumps substantially in constant preselected relationship with each other, by-pass means effective to maintain the value of said sum of said torque loads when said failure occurs, said by-pass means being effective in the event of said failure to increase the torque load of one pump an amount corresponding to the value of said torque load normally carried by said pump rendered inoperative by said failure, and means connected to said control lever for overriding said control means and said by-pass means to vary said value of the sum of said respective torque loads, whereby the speed of said mechanism varies as a func- {ion of said control pressure and said control ever.

11. Pump control apparatus for an internal combustion engine having associated therewith a compressor and a conduit for delivering combustion air and fuel respectively thereto, a source of said fuel connected to said conduit, means for regulating the speed of said engine by the rate of fuel flow from said source to said engine, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of fuel flow in said conduit, comprising: a pair of pumps in series in said conduit for producing said fuel flow, means responsive to said control pressure and to an air pressure in said engine for regulating said fuel pressure so that the value of said fuel flow is said se lected function of said control pressure, Whereby said engine speed is a function of said control pressure and has a desired value.

12. Pump control apparatus for an internal combustion engine having associated therewith a compressor and a conduit for delivering combustion air and fuel respectively thereto, a source of said fuel connected to said conduit, means for regulating the speed of said engine by the rate of fuel flow from said source to said engine, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of fuel flow in said conduit, comprising: a pair of pumps in series in said conduit for producing said fuel flow, first means responsive to said control pressure and to an air pressure in said engine for regulating both the pressure in said conduit between said pumps and said conduit pressure downstream from said pumps, as predetermined functions of said control pressure, and second means in said first means for maintaining a substantially constant preselected relationship between the respective values of said regulated pressures in said conduit, whereby said engine speed is a function of said control pressure and has a desired value.

13. Pump control apparatus for an internal combustion engine having associated therewith a compressor and a conduit for delivering combustion air and fuel respectively thereto, a source of said fuel connected to said conduit, means for regulating the speed of said engine by the rate of fuel flow from said source to said engine, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of fuel flow in said conduit, comprising: a primary pump and a secondary pum in said conduit for producing said flow, said secondary pump being downstream from said primary pump, first mean responsive to said control pressure for regulating the pressure downstream from said primary pump as a preselected function of said control pressure, second means responsive to said control pressure and to an air pressure in said engine for regulating said conduit pressure downstream from said secondary pump as said predetermined function of said control pressure; said respective pressures downstream from said primary and said secondary pumps being in a pro-established substantially constant relationship with each other; and third means effective, when said primary pump fails so that the normal supply of fuel from said primary pump to said secondary pump is diminished more than a predetermined amount, to connect the inlet of said secondary pump to said source for flow of fuel therebetween at a rate which compensates said diminished supply, the sum of the respective pressure differential across said pumps remaining substantially constant regardless of said primary pump failure; whereby said engine speed is a function of said control pressure and has a desired value which is not affected by said failure of said primary pump.

14. Pump control apparatus for an internal combustion engine having associated therewith a conduit for delivering fuel thereto, a source of said fuel connected to said conduit, means for regulating the speed of said engine by the rate of fuel flow from said source to said engine, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of fuel iiow in said conduit, comprising: a primary pump and a secondary pump in said conduit for producing said flow, said secondary pump being downstream from said primary pump, first means for regulating the pressure downstream from said primary pump as a preselected function of said control pressure, second means for re ulating said conduit pressure as said predetermined function of said control pressure, said first and second means being normally effective to maintain the ratio between the respective values of said downstream pressures a substantially constant preselected value; and third means effective, when said secondary pump fails so that the normal delivery thereof to said conduit is diminished to an extent which renders said second means ineffective to maintain said conduit pressure as said predetermined function of said control pressure, to connect the outlet of said primary pump directly to said conduit for the flow of fuel directly therebetween; said primary pump thereby being effective, in the event of said secondary pump failure, to compensate for said failure and to maintain the value of the sum of the respective diiferentials across said pumps in a pro-established relationship with the value of said control pressure, said value of said sum being unaffected by said failure, whereby said engine speed is a function of said control pressure and has a desired value which is not affected by said failure of said secondary pump.

15. Pump control apparatus for an internal combustion engine having associated therewith a conduit for delivering fuel thereto, a source of said fuel connected to said conduit, means for regulating the speed of said engine by the rate of fuel flow from said source to said engine, and a device for producing a control pressure in said apparatus which is a selected function of the desired rate of fuel flow in said conduit, comprising: a primary pump and a secondary pump in said conduit for producing said flow, said secaoooncs ondary pump: being downstream from: said pri+ ma-ry pump, first meansfor regulating the pres? suredownstreamfrom said primary pump a-sza preselected function of saidcontrol pressure, sec-. nd means for regulatingsaid conduit pressure as" said predetermined function of, said control pressure, said first and second means beingznormally effective to maintain the ratio between the respective valuesof said-downstream pressures a substantially-constant preselected value; third means effective,- when either of said pumps. fails todeliverusufiicient fuel therethrough to main. tain said value .of said. regulated pressure dowm stream-therefrom, to connectwthe other of said pumps directly between said source and saidlconq d-uit thereby rendering said other pump subject tea-pressuredifferential having a value .greater than normalv by an amount equalito the correspending". decrease of the pressures differential across--said failed pump; said conduitupressure beingunaffected bysaid pump failure; and manually operated means: foroverriding said-'sfirst and second means to vary said respective .downstream pressures or the effective area of flow through said. conduit so, that the fuelv flow is varied by said manually operated means, where.- by the engine speed isnormally a function of said control pressure and has a predetermined value not affected by failure ofeither of said pumps and wherebysaid'speed also a function of said overriding means.

16;Pump control apparatus for an internal combustion engineohaving associated therewitha conduitgfordelivering fuel thereto,. avsource of said fuel: connected to said conduit, mean for regulating the speediof saidiengine by the. rate of fuel'flow fromrsaidisou-rcelto said-engine, a device for producing a. control pressurev in said apparatus which. is a selected function of the desiredrate of'fuel flowinsaid conduit; "and a manually operated .pu-mp control lever; comprising: aiprimarypumpiandla secondary pumpcin said I 'conduittfor producing said lflovv, said; secondary pump :being. downstream from :saidpr-im-ary pump, first means for flowingfuelfrom theadown'stream side .of said-:primaryw pump to said: source, second means insaid first-meansfor controlling the iflowtlrerethrough'ito regulate thepressure: downstream; fromv said primary pump as -a preselected function V. of i 'saidcontrol pressure,.third;means.for flowing fuel fromsaidiconduit-to said source; fourth.means in-sai d third means for; regulatingithe flow therethrough as apredetermined function of i said control pressure, fifthzmeans for the flow of fuel from the downstreamiside. of'said primary pump to,-said conduit, sixth means forthe how of fuel from said source to. the inlet of said secondary pump, seventh-and eighth means respectively indsaid. fifth: and sixth means for regulating. the flow therethrough in response to the respective pressure --difterentials thereacross, said seventh and, eighth means being normally effiective to prevent flowtherethroughwhen the respective'values of thepressures downstream from said primary and secondary pumps are determined bysaid pre selected and said predetermined functions of said control pressure; said seventh means-being effective, when the delivery through saidsec ondary pump decreases as a result of failure thereof so that said'fourth meanscannot regu-- late said-conduit pressure as said predetermined function'ofsa-id controlpressure, to permit-flowth'rough'said'fifth means so that said-primary pump-delivers-an amount offuel-directly to said conduit :equal to'ztheiamount :ofdsaid secondary pumps delivery decreasertherebyzmaintainingmaid conduit pressure: at; theevcluez-corresponding to said" predetermined: function ofza-said'oontrol pressure, a connection betweenasaid'isecond and fourth:..means. for .renderingsaid seoondi means subj ect f-to overrideacontrol. day said .ifourth :means when saidi'secondaryspump failure 2 occurs; said eighth meansabeingi effective, when corresponds ing failurezof said primary pump occursptoiper mit now through said sixth means-:soothattsaid secondary pump obtains an. amounttof fuel di rectly fr onr said :source equal to" the-:amountfioi the-primary pump deliveryi decrease thereby maintaining said conduit r pressure: at the value corresponding. to said preselected r function :1 of said control pressure; th'eisum lot the respective pressure differentials across lsaid :primaryr and secon dary r pumps remaining: substantially; constant at any given value of said control pressurel regardless: of the occurrence "-or of 'the -extenti of fai-Iureofeither 'of 'saidlpum-psz and valve=means connected to: said control lever: for overriding said 1 secondand fourth meansddr: varyingzt-th'e flowin either said first andsaid thirdsmeans or in said -cond-uitg respectively, to :vary said-monedui-t new. from a' zero 1 Valuercorrespondingrto a predetermined cut-off position-of lsaid lever: to a value corresponding to a predetermined femera gencylever position"at which' said condui-ttfiow is the maximum producible: by said pumps-;.=l whereby the engine speednormal-lyahasradsiredr value' that is a function of said' control-pressure; failure-of -=either =of i said' pumps is compensated by theother-Without affecting the enginesspeed and the engine speed is subj ect to= override con? trol bymanual opera-tion of said lever:

17. Fluid pumping apparatus comprising a-;pair; o'ffipu-mps connected series,- a: relief valve for regulating -tlre=- discharge= pressureof tlie ffi st' pump 'at a' first predeterminedvaluepa coatrob valve or controlling the: discharge pressureot the second pumpat a'secondpredetermir red value greaterutham said" first value-, lby pass means associated with =ea'clrpump -so that -if one pumpfa-i ls the-'other' -can' pump fluid th rw the by -pass: means ofthe failed pump; and means-leffeotivei upon failure-of i said second pump-toplace said-- control "valve in conjtrol-of-the dischargepressuree charge-- pressure from" the second pu-mp' occurs upon'failure'of'that'pump;

18;. Fluid pumping apparatus; comprising-mst and second pumps ,for delivering "fluid to a discharge conduit first relief valve; means forreg ulating the discharge pressure of s'aid' first -pum'pat a zfirst predetermined 1 value, control valve means for regulating" the discharge; pressure of said second pump at al' gsecondpredetermined value higher than said firstlvalne; seo'ondrelieff valve. means for regulating the';di"scharge pres= surelof Tsaid first pump at-substantially said second value and means. responsive to'the discharge pressure of said second pump for transferring; control ofjsaid first pump'fromsaidfirst relief:- valve" means to? said secondrelief valve means-7 upon failure of said-seoond'pump.

'19. Fluidpump apparatusfor a-ro-tating mecl'i anism having associatedtherewith a -source-=:ofiifluid} a conduit for supplying: fiuid'i'fromz-saidu source-to said mechanism "for. rotation) thereofii; means =for: rotating: said: imechanism at {a speed: determined'byxtheerateooflzfluid flow, .and;a=cori-;- troll devices for; producing acontrol 1 pressure 2 in; said i apparatuswh-ich 2 controls the: rates ref ,sazict fluid flow and hence the speed of said mechanism; comprising: a pair of pump connected in series for delivering fluid from said source to said conduit, means responsive to said control pressure for regulating the delivery of said pumps so that said fluid flow to and the speed of said mechanism is always a selected function of said control pressure.

20. Fluid pump apparatus according to claim 19, including a manually operated cutoff valve in said conduit for cutting off the flow of fluid from said pumps to said mechanism, and means for regulating the fluid pressure in said conduit during cutoff as a predetermined function of said control pressure, whereby no abnormal strain is produced in said apparatus by the closing of said cutofl valve.

21. Fluid pump apparatus according to claim 19, including a relief valve, responsive to said control pressure, for normally regulating the fluid pressure between said pumps at a value approximately equal to the value of said control pressure.

22. Fluid pump apparatus according to claim 19, including a control valve responsive to said control device pressure for normally regulating the fluid pressure in said conduit at a value approximately equal to twice the value of said control device pressure.

23. Fluid pump apparatus according to claim 19, including a relief valve for normally regulating the fluid pressure between said pumps at a value approximately equal to the value of said control device pressure, and a control valve for normally regulating the fluid pressure in said conduit at a value approximately equal to twice the value of said control device pressure, both of said valves being responsive to said control device pressure, whereby both of said pumps operate with one-half the total pumping load and approximately the same efliciency and the life expectancy of each pump is thereby doubled.

24. Fluid pump apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of fluid flow, and a control device for producing a control pressure in said apparatus which controls the rate of said fluid flow and hence the speed of said mechanism; comprising: a pair of pumps connected in series for delivering fluid from said source to said conduit, and means responsive to said control pressure for regulating the delivery of said pumps so that said delivery remains the same in the event of failure of either of said pumps, whereby the said fluid flow to and the speed of said mechanism is always a selected function of said control pressure.

25. Fluid pump apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of fluid flow, and a contro1 device for producing a control pressure in said apparatus which controls the rate of said fluid flow and hence the speed of said mechanism; comprising: a pair of pumps connected in series for delivering fluid from said source to said conduit, said pumps being so arranged that each normally performs substantially one-half of the total pumping load, and means responsive to said contro1 pressure for regulating the delivery of 22 said pumps so that said delivery remains the same in the event of failure of either of said pumps, whereby the said fluid flow to and the speed of said mechanism is always a selected function of said control pressure.

26. Fluid pump apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof, means for rotating said mechanism at a speed determined by the rate of fluid flow, and a control device for producing a control pressure in said apparatus which controls the rate of said fluid flow and hence the speed of said mechanism; comprising: a pair of pumps connected in series for delivering fluid from said source to said conduit, a relief valve for regulating the fluid pressure between said pumps, and means responsive to said control pressure for operating said relief valve and regulating the delivery of said pumps so that said delivery remains the same in the event of failure of either of said pumps, or said relief valve, whereby the said fluid flow to and the speed of said mechanism is always a selected function of said control pressure.

27. Fluid pump apparatus for a rotating mechanism having associated therewith a source of fluid, a conduit for supplying fluid from said source to said mechanism for rotation thereof. means for rotating said mechanism at a speed determined by the rate of fluid flow, and a control device for producing a control pressure in said apparatus which controls the rate of said fluid flow and hence the speed of said mechanism; comprising: a pair of pumps connected in series for delivering fluid from said source to said conduit, a control valve for regulating the fluid pressure in said conduit, and means responsive to the control pressure of said control device for operating said control valve and regulating the delivery of said pumps so that said delivery remains the same in the event of failure of either of said pumps or of said control valve, whereby the said fluid flow to and the speed of said mechanism is always a selected function of said control pressure.

28. Fluid pump apparatus according to claim 19 including a control valve, responsive to said control device pressure and a fluid pressure in said mechanism, for normally regulating the fluid pressure in said conduit.

29. Fluid pumping apparatus comprising a pair of pumps adapted to receive fluid from a common source and to deliver said fluid to a common discharge conduit under a selected pressure at a selected pump speed; means to regulate the operation of said apparatus so that the normal discharge pressure of one pump is constantly maintained at a predetermined fixed ratio to the normal discharge pressure of the other pump at all operating speeds; and means whereby either pump will automatically continue to discharge fluid through said conduit at said selected pressure in case the other pump fails to function normally.

30. Fluid pumping apparatus according to claim 29, wherein the normal discharge pressure of one pump is constantly maintained at a value of one-half the discharge pressure of the other pump.

31. Fluid pumping apparatus according to claim 29, having means whereby both pumps always operate at equal speeds until one pump fails completely, after which the other pump automaticadlyracontinuesz-s to: operate lwithout z-intem motion 32$:Eluid pumping appamatuso according. to claim :31, EhENiIlgLIIlGflIISfWVhQIBbYF bOth apum psi are driven by a. commonidrivc shaftmhichuponzcom: pieteifadlurec of: one;pump;w automatically .contmuesiitmdrivefthezzother pumpswithoutsintermpr ti'orn.

33$.Eluida pumping zapparatus comprisinga padr eof; pumpslcomectedlin aserieszzandiadapted tu'zreceiveofluidi from a:- common source-.130 deliverrsaid fiuidoto a; common'.-.discl1arge:condnit underz: aaselectedz pressure; at, t a ..selected.;:pnmp speech": meaznsu to"; regulate the: operationuoffxsaid apparatuszzso .that zthectotal pumping cloadaissnor; mallmdividect equallmbetween; both pmnpswat operating-speeds; and means 101;- making eithem-numpr, automaticallm assume; theji total plimpingiloadvuponacompleteifailure .oiathezother numnc SQ Eh-iidi pumping; apparatus according: to claim fia; ,havin pmeansv whereby; uponathe: par:- ttalg'failureigofioneapump the other pump automatically; assume i such part 1 of the; totazl pumping load-as,requiredytozalways maintainzthe normahdischargezof 1saitl:apparatus 35,1 Fluid. pumping; apparatus according: to claim 33;;,havin meansgwhereby bothwpumpseale wayszoperategat-equal speedszuntil oneapumpxfails completely, after 1 whiohpthe ;=other: pumpyantcx-e matically; continues ;to zoperate;withoutsintermpe tiaonx,

6. F1uidi pump n apparatus accor ifl t claim;33 ,1 having :means; whereby; both pumpsuare driven:;by;;-a common;- drive-shaft which, upon complet f allure-:05 onemump; automatically-non,- tirmes tqt vdrive; the: other: pump without: inter, up zione 5 38;;Fluict pumping apparatus-s. according. to

claln'w33; having means whereby,iupon; partial onztotaliailurerofzonemump, thecdischarge .Of'jth$ other pump is partially or totallyrvbwmssed. amund'itheufirst pump.

o 39; Eluidv pumping apparatus: according ,to

claim 133; whereinzbotht zpumps; normally operate in useris: with: .each anther:

40:F11'1'id5 pumping; apparatus according to claim 39; :havingrmeansswhereby;upomthe 5 failureunof one pump, bothilpumgs operate pare tia'lly:imseries:andfpartiadlydmparallel;

nerar n s cmd in-- the=- mmor my patent v rrEnistrA'rEsimmrrst Number Name; Date;

868,718 Smith O0t-;22;;;l90i 1,052,5885h Janickt: i Fb; .11, 191 0 vickecsianuunn- SentL13m1932 1,9455632; Flanders- .Eeb. 6:198:11 1 970380 '1 Hosel l i cAug. :14; L193! 2:,07839583 Ilyshodms," May": .4-',-..193fi 2,108,771 Laird -i.E$b.'x15,?;1938

Chandlers---Mu l--- Nov. '5, A 1946 

